Abstract
The use of recycled plastics from fisheries for new technical applications faces several challenges due to heterogeneous polymer composition, incompatibility of materials, contamination, and polymer degradation as the main barriers preventing efficient recycling and high‑value reuse of plastics [1]. A central issue is the complex and mixed polymer composition of fishing gear, which is typically composed of multiple polymers such as PE, PP, PA, PET, and sometimes metals (e.g. steel cores or lead lines). This heterogeneity complicates recycling preventing joint processing in the same recycling stream. For example, demersal seine ropes often consist of PE/PP blends combined with steel cores, and dolly ropes may include PE/PP/PET mixtures, making them effectively non‑recyclable and leading to incineration or landfill [2]. Material degradation is another key barrier. Plastics from fisheries are exposed to UV radiation, abrasion, and marine conditions, leading to oxidation, reduced molecular weight, and inferior mechanical properties [3-4]. Consequently, recycled polyolefins (PE/PP) often exhibit lower strength, restricting their use to lower value or “downcycled” products rather than high performance technical applications. Contamination further complicates reuse. Recovered gear often contains biofouling, sand, organic residues, and hazardous substances (e.g. copper coatings or heavy metals), requiring extensive cleaning and sometimes preventing recycling entirely. Finally, the variability in polymer composition creates uncertainty for manufacturers. Recyclates derived from mixed streams lack predictable and reproducible material properties, which is critical for sectors such as automotive or engineering plastics. This inconsistency, combined with limited infrastructure and unclear material specifications, makes it difficult to use recycled fishing plastics for new technical applications [1].
Challenges with recycled plastics from fisheries can be addressed through design and system improvements. Fishing gear should be standardised to single polymers, enabling easier recycling. Advanced sorting, cleaning, and traceability systems must reduce contamination and variability. In addition, chemical recycling and compatibilisation technologies can upgrade mixed plastics. Finally, stronger collaboration across the value chain and material certification can ensure consistent quality suitable for technical applications [1].
[1] C. W. Karl et al., The role of recycling and biodegradable materials in aquaculture and fisheries, chapter 9 in Managing Marine Plastic Pollution in Norway, Routledge (2026).
[2] E. Grimaldo/C. W. Karl et al., Reducing plastic pollution caused by demersal fisheries, Marine Pollution Bulletin, 196 (2023), 115634.
[3] C. W. Karl et al., Degradation Behavior of Biodegradable and Conventional Polymers for Gill Nets, Exposed to Accelerated Aging, ACS Applied Polymer Materials, 7 (2025), 2830.
[4] C. W. Karl, S. Hakvåg, Degradation behaviour of biodegradable and conventional monofilaments under marine field and laboratory conditions, European Polymer Congress (EPF), Groningen (2025).
(directly taken from the abstract)